An enhanced version, the Long March 3B/E or G2, was introduced in 2007 to increase the rocket's GTO cargo capacity and lift heavier GEO communications satellites. The Long March 3B also served as the basis for the medium-capacity Long March 3C, which was first launched in 2008.

As of January 2018, the Long March 3B and 3B/E have conducted 41 successful launches, plus one failure and two partial failures, giving them a success rate of 93.2%.

History

Diagram of the Long March 3B, showing its outboard liquid rocket boosters.

The development of the Long March 3B began in 1986 to meet the needs of the international GEO communications satellite market. During its maiden flight on 14 February 1996 carrying the Intelsat 708 satellite, the rocket suffered a guidance failure two seconds into the flight and destroyed a nearby town, killing at least six people,[5] but outside estimates suggest that anywhere between 200 and 500 people might have been killed.[6] However, the author of the report[6] later ruled out large casualties, because evidence suggest that the crash site was evacuated before the launch.[7]

The Long March 3B and 3B/E rockets conducted ten successful launches between 1997 and 2008.[2]

In 1997, the Agila 2 satellite was forced to use onboard propellant to reach its correct orbit because of poor injection accuracy on the part of its Long March 3B launch vehicle.[8] In 2009, a Long March 3B partially failed during launch due to a third stage anomaly, which resulted in the Palapa-D satellite reaching a lower orbit than planned.[9] Nonetheless, the satellite was able to maneuver itself into the planned orbit. The Long March 3B and its variants remain in active use as of January 2014, having conducted a total of 23 consecutive successful launches.

In December 2013, a Long March 3B/E successfully lifted Chang'e 3, China's first Lunar lander and rover into the projected lunar-transfer orbit.

Design and variants

The Long March 3B is based on the Long March 3A as its core stage, with four liquid boosters strapped on the first stage. It has an LEO cargo capacity of 11,200 kilograms (24,700 lb) and a GTO capacity is 5,100 kilograms (11,200 lb).

Long March 3B/E

The Long March 3B/E, also known as 3B/G2, is an enhanced variant of the Long March 3B, featuring an enlarged first stage and boosters, increasing its GTO payload capacity to 5,500 kilograms (12,100 lb).[10] Its maiden flight took place on 13 May 2007, when it successfully launched Nigeria's NigComSat-1, the first Africangeosynchronouscommunications satellite. In 2013, it successfully launched China's first lunar lander Chang'e 3 and lunar rover Yutu.

Since 2015, the Long March 3B and 3C can optionally accommodate a YZ-1 upper stage, which has been used to carry dual launches or BeiDou navigation satellites into medium-Earth orbit.

Long March 3C

A modified version of the Long March 3B, the Long March 3C, was developed in the mid-1990s to bridge the gap in payload capacity between the Long March 3B and 3A. It is almost identical to the Long March 3B, but has two boosters instead of four, giving it a reduced GTO payload capacity of 3,800 kilograms (8,400 lb). Its maiden launch took place on 25 April 2008.

Launch failures

Intelsat 708 launch failure

On February 14, 1996, the launch of the first Long March 3B with Intelsat 708 failed just after liftoff when the launch vehicle veered off course and exploded when it hit the ground at T+23 seconds. At least 6 people on the ground were killed by the explosion.[11] The cause of the accident was traced to short-circuiting of the vehicle's guidance platform at liftoff.

The participation of Space Systems/Loral in the accident investigation caused great political controversy in the United States, since information provided during the accident investigation would help China improve its rockets and ballistic missiles. The U.S. Congress reclassified satellite technology as a munition and placed it back under the restrictive International Traffic in Arms Regulations in 1998.[12] No license to launch U.S. spacecraft on Chinese rocket has been approved by the U.S. State Department since then, and an official at the Bureau of Industry and Security emphasized in 2016 that "no U.S.-origin content, regardless of significance, regardless of whether it’s incorporated into a foreign-made item, can go to China."[13]

Palapa-D partial launch failure

On August 31, 2009, during the launch of Palapa-D, the third stage engine under-performed and placed the satellite into a lower than planned orbit. The satellite was able to make up the performance shortfall using its own engine and reach geosynchronous orbit, but with its lifetime shortened to 10.5 years. Investigation found that the engine's gas generator suffered a burn-through due to ice blockage in the engine's liquid-hydrogen injectors.[14]

ChinaSat-9A partial launch failure

On June 19th, 2017,a Long March 3B/E mission carrying ChinaSat-9A ended in partial failure. Officials refused to release details regarding the status of the mission until about 13 hours after liftoff. Officials then confirmed that the mission had been anomalous and that an anomaly had been detected in the performance of the vehicle's upper stage due to which the intended orbit had not been attained, while analyzing the vehicle's telemetry. Investigation found a failure in third stage's Rolling Control Thruster during the glide phase left the payload in a lower than intended orbit. The payload spent two weeks reaching its intended orbit under its own power.[15]

References

^ abcMark Wade. "CZ-3B". Encyclopedia Astronautica. Archived from the original on 19 March 2008. Retrieved 26 April 2008.

^Select Committee of the United States House of Representatives (3 January 1999). "Satellite Launches in the PRC: Loral". U.S. National Security and Military/Commercial Concerns with the People's Republic of China. Retrieved 23 May 2012.

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